Jens Geyer created THRIFT-6187:
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Summary: Replace the five obsolete autoconf macros in configure.ac
Key: THRIFT-6187
URL: https://issues.apache.org/jira/browse/THRIFT-6187
Project: Thrift
Issue Type: Improvement
Components: Build Process
Reporter: Jens Geyer
Every run of ./bootstrap.sh emits five autoconf obsolescence warnings. On a
clean tree at 569e4df2a, with autoconf 2.71 / automake 1.16.5 / libtool 2.4.7
as shipped by ubuntu-24.04:
{code}
configure.ac:87: warning: The macro `AC_PROG_LIBTOOL' is obsolete.
configure.ac:91: warning: AC_PROG_LEX without either yywrap or noyywrap is
obsolete
configure.ac:603: warning: The macro `AC_HEADER_STDC' is obsolete.
configure.ac:604: warning: The macro `AC_HEADER_TIME' is obsolete.
configure.ac:606: warning: The macro `AC_TYPE_SIGNAL' is obsolete.
{code}
h2. Why this is worth a ticket rather than ignoring
They are not just log noise. The lib-java-kotlin job runs
{{actions/setup-java}}, which registers a javac problem matcher, and later runs
{{./bootstrap.sh}}. Autoconf's {{file:line: warning: text}} output happens to
match that matcher, so GitHub turns the warnings into *file annotations* and
paints an alert marker next to configure.ac in the "Files changed" view of any
PR that touches it. Nobody wrote a check for this; it is an accidental
cross-hit between a Java matcher and autoconf's output, and it makes an
untouched, unrelated file look like it has findings. It confused a reviewer on
PR #3800.
h2. The changes
|| line || now || replacement || note ||
| 87 | {{AC_PROG_LIBTOOL}} | {{LT_INIT}} | aclocal/libtool.m4:99 already
carries {{AU_ALIAS(@<!---->[AC_PROG_LIBTOOL], @<!---->[LT_INIT])}}, so this is
a rename with no behaviour change. configure.ac:87 is the only call site. |
| 91 | {{AC_PROG_LEX}} | {{AC_PROG_LEX(@<!---->[noyywrap])}} | {{noyywrap}} is
not a guess: compiler/cpp/src/thrift/thriftl.ll:105 already declares {{%option
noyywrap}}. |
| 603 | {{AC_HEADER_STDC}} | delete | |
| 604 | {{AC_HEADER_TIME}} | delete | |
| 606 | {{AC_TYPE_SIGNAL}} | delete | |
h2. Three things to check before deleting anything
# *The three deletions are safe because nothing consumes their output.*
{{STDC_HEADERS}}, {{TIME_WITH_SYS_TIME}} and {{RETSIGTYPE}} appear only inside
checked-in generated config.h files (lib/cpp/src/thrift/config.h,
lib/c_glib/src/thrift/config.h, lib/php/src/ext/thrift_protocol/config.h). No
hand-written source guards on any of them.
# *Do not confuse AC_HEADER_TIME with HAVE_SYS_TIME_H.* That one _is_ used in
real code -- lib/cpp/src/thrift/server/TServer.cpp:22 and
lib/cpp/src/thrift/transport/TFDTransport.h:24 both {{#ifdef}} on it. It comes
from {{AC_CHECK_HEADERS(@<!---->[sys/time.h])}} at configure.ac:642, which
stays. Deleting AC_HEADER_TIME does not touch it.
# *No AC_PREREQ bump is needed.* The argument form of AC_PROG_LEX was
introduced in autoconf 2.70, and configure.ac declares {{AC_PREREQ(2.65)}}
while build/docker/ubuntu-focal still ships autoconf 2.69. Checked: 2.69
accepts {{AC_PROG_LEX(@<!---->[noyywrap])}}, ignores the argument and generates
configure normally (exit 0). So the fix is effective on 2.70+ and harmless on
2.69, and AC_PREREQ can stay where it is.
h2. Out of scope
The same bootstrap run also produces roughly forty automake warnings of the
form {{test/rb/Makefile.am:36: warning: user target 'distdir' defined here
...}}, across test/ and tutorial/. Different tool, different cause, much larger
blast radius -- that belongs in its own ticket if anyone wants it.
h2. Verification
autoconf reports zero warnings for configure.ac after the change, and
{{./bootstrap.sh && ./configure && make}} still succeeds. Worth confirming on
ubuntu-focal (autoconf 2.69) as well as noble, since those are the two ends of
the supported range.
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